Swathing means for infants



Nov. 9, 1965 c. DEvAUD SWATHING MEANS FOR INFANTS Filed Oct. 24, 1962 United States Patent O 3,216,421 SWATHING MEANS FR INFANTS Charles Devaud, Geneva, Switzerland, assigner to Societe Anonyme de lAncienne Maison Devaud, Kunstle & Co., Geneva, Switzerland Filed 9ct. 24, 1962, Ser. No. 232,828 9 Claims. (Cl. 12S-284) This invention relates to swathing means for infants and more particularly to an inner layer thereof which is to be placed between the infants skin and an absorbent outer layer which, if desired, may in its turn be covered with an impermeable wrapping. The purpose of such inner layer is to permit, on one hand, the passage of liquid such as urine from the yinfan'ts body to the said absorbent outer layer while preventing, on the other hand, the return of such liquid from the outer layer in which it has been absorbed, towards the infants skin.

In my U.S. Patent No. 2,894,511, dated July 14, 1959, I have already suggested this arrangement of layers in swathing means for infants and the provision of an inner layer of looped fabric made from non-absorbent, waterrepellent fiber material such as polyvinyl chloride, said fabric being further characterized by forming a plurality of interstices having cross-sectional areas of a magnitude normally to prevent the liow of liquid therethrough by the surface tension of said liquid with respect to the surfaces of said interstices.

The present invention relates to a further development of the swathing means of my said patent.

The main, though not the sole object of my invention is to provide a swathing means of the said kind having an inner layer which is more resistant to the high temperatures encountered in laundering, which is still less absorbent and more repellent to water, and which can be manufactured from liner fibers and finer yarns than the inner layer of looped fabric made from polyvinyl chloride fiber material of my former invention.

A preferred embodiment of the present invention will now be described by way of example with reference to the accompanying drawing, in which:

FIGS. 1 to 4 illustrate the general arrangement of swathing means embodying the inner layer according to the invention, in which these swathing means are in the shape of a triangular composite diaper at various stages of its preparation;

FIG. shows the structure of the looped fabric of the inner layer embodying the invention in such a swathing means;

FIG. 6 shows a portion of a hypothetical woven fabric which can be assimilated to the looped fabric of the invention for the purpose of assessing the cross-sectional area of the loop interstices; and

FIGS. 7 to 10 diagrammatically illustrate the progress of a droplet of liquid from the infants skin to the absorbent pad in the swathing means of the invention.

The composite diaper-illustrated in FIGS. 1 to 4 comprises a triangular piece 1 of looped fabric, knitted from yarn consisting of polypropylene or other suitable polyolefin fibers and which will be described in more 'detail below. Along its side 2, the triangular piece of knitted fabric 1 is sewn to a supple cover piece 3 which may be made from rubber-like or other impermeable sheet material. The shape of cover piece 3 conforms with that of the triangmlar piece 1. As shown in FIG. 2, a pad 4 of rectangular shape, made from absorbent material, for instance from cellulose material, is loosely placed on the 3,216,421 Patented Nov. 9, 1965 JCC inner face of the cover piece 3 in such a way that the middle plane of the pad approximately coincides with a line (not shown) running at right angles to the seam line 2 through the opposite apex of the cover contour.

The composite diaper is then completed by swinging the triangular piece 1 of knitted fabric upwards about the seam line 2 as shown in FIG. 3, and by turning it over on the cover piece 3 as shown in FIG. 4. The absorbent pad 4 is then retained between `the inner piece 1 of knitted fabric and the outer cover piece 3. The composite diaper, which may comprise a swathing band as shown in dashand=dot lines at 5, is then ready for use. After use, the absorbent pad 4 may be removed and replaced by a fresh one.

The essential element of the described composite diaper is the piece of knitted fabric 1 which serves for controlling the passage of liquid between the infants skin and the absorbent pad 4 and which will now be described in more detail with reference to FIGS. 5 and 6.

The piece of fabric 1 is knitted from yarn 6 consisting of polyolefin fibers and more particularly of polypropylene staple fibers 7. Such fibers are available with a count of about 2.6 deniers, while the polyvinyl chloride fibers hitherto used for similar purposes are about 4 deniers. Also, polyolefins are specifically lighter than polyvinyl chloride, their specific weight being in the order of 0.90 to 0.95, especially 0.90 for polypropylene, against 1.38 for polyvinyl chloride. The yarn 6 used according to this invention should have a total denier of not less than 285 deniers but not more than 450 deniers (in metrical count, between 20 and 32 ykilometers per kilogram). A preferred example `of such yarn is one twisted from two strands 8, 8 of polyolefin fibers, each strand weighing 188 deniers (24 kilometers per kilogram); this yarn has an ultimate apparent diameter d of about 0.012 inch (0.3 mm.).

Preferably, the fabric 1 should have a substantial thickness and therefore it is preferred that it be knitted rather than woven and a fabric knitted in conventional 1:1 ribbed fashonas shown in FIG. 5 is most suitable. It has been found that with yarn made from polyolefin fibers, a number of conditions is quite critical if best results are to be obtained.

Firstly, the number of the Wales 9 per inch should be comprised between 0.5 and 0.7 the number of courses 10 per inch of the loops in the fabric. For instance, in a preferred example the fabric may comprise 30 courses per inch (12 courses per cm.) as measured in a vertical or Wale-wise direction, and 18 wales per inch (about 7 wales per cm.) as measured in a horizontal or coursewise direction.

Secondly, the average cross-sectional area of each loop interstice such as 11 (disregarding the narrow interstices such as 11a and 11b within the wales 9) should be not less than 750 millionths of a square inch (0.5 sq. mm.) to ensure proper passage of the liquid but not more than -1100 millionths of a square inch (0.7 sq. mm.) t-o provide the desired capillary effect of the yarn surface on the liquid within the loop passage. This cross-sectional area of the loop interstice 11 can be assessed by any proper method approaching the actually prevailing conditions.

As an example of such a method, each loop interstice could be assimulated to the rectangular interstice 12 between the warp yarns 13 and the weft yarns 14 of a hypothetical fabric 15 Woven from the same yarn 6, shown in FIG. 6 at the same scale as the looped fabric of FIG. 5. Thus, assuming the woven fabric in FIG. 6

to represent the looped fabric of FIG. 5 with the preferred yarn size and stitch division referred to above, this woven fabric will have 18 warp yarns per inch (7 per cm.) and 30 weft yarns per inch (12 per cm.), each yarn with a diameter of 0.012 inch (0.3 mm.). Thus, there are 18 30=540 interstices in a square inch. In that same square inch, 18 inches of warp yarn and 30 inches of weft yarn are used and their projection covers an area of which is well between 750 and 1100 millionths of a square inch as called for.

The third condition to be observed results from the fact the water repellent properties of the bers are related to the thickness of the yarn so that the limits of the interstice area should also be modified according to the count of the yarn used. This condition requires the said area of each loop interstice to be comprised not only between 750 and 1100 millionths of a square inch (0.5 to 0.7 sq. mm.) but also between 2.4 and 2.75 millionths of a square inch per denier of the yarn. In terms of the metric system, the product of the interstice area and the total metric count of the yarn (kilometers per kilogram) should be comprised between 14 and 16. Since in the above preferred examples, yarn of 375 denier is used, the area per interstice should amount to between 2.4X375 and 2.75 375, that is to between 900 and 1060 millionths of a square inch. It can be seen that in the present instance this third requirement is more stringent than the second one but still is fulfilled in the preferred example, according to the assessment of its interstice area at 930 millionths of a square inch.

FIGS. 7 to l0 illustrate the looped fabric 1.

It will be noted that the polyoletin and more particularly the polypropylene fibers and the yarns made from them are both non-absorbent and repellent to water and such aqueous solutions as urine. The non-absorbent property of these fibers consists in thatthey do not absorb any water or aqueous solution in themselves such as by swelling; while cellulosic fibers, cotton, and to a lesser degree wool, are examples `of absorbent fibers, typical examples of substantially non-absorbent fibers are those consisting of glass, nylon or polyvinyl chloride.

On the other hand, liquid-repellent fibers are fibers on contact of which the surface tension causes the liquid to form a convex meniscus, as distinct from liquidattracting materials on contact of which the surface tension causes the liquid to form a concave meniscus. For instance, glass fibers are repellent to mercury but are attracting to water, as are not only the water-absorbent fibers such as cotton and degreased wool but also other non-absorbent fibers than glass, such as nylon fibers.

effect of the inner layer of However, polyvinyl choloride fibers are both non-absorbent and repellent to water, as are the polyolens, e.g. polypropylene, fibers which come into consideration for the present invention.

Each of FIGS. 7 to 10 represents a greatly enlarged 'cross-section through two parallel yarns 6 of the inner vlayer of looped fabric 1 in the composite diaper of FIGS. 1 to 4, with adjacent surface portions of the babys skin at 16 and of the absorbent pad 4. These yarns 6 are separated by a narrow interstice in a loop of the fabric to which they belong, such as the interstice 11 in FIG. 5, the cross-sectional area p f which complies with the abovestated conditions.

It is now Vassumed that a droplet of urine or sweat secreted by the infant occurs at 17 in the upper part of the interstice 11 on the infants skin 16. Since the skin as well is water-attracting, the droplet rst adheres to it but as it is pressed by the infants weight into the interstice 11 formed by the water-repellent yarns 6, it forms a convex meniscus 8 at the neck of the interstice (FIG. 7). Such a convex meniscus tends to move into the free space in fr ont of it, and thereby draw the droplet 17 towards the absorbent pad 4, as shown in FIG. 8. Thereby, the rear surface of the droplet forms a secondary convex meniscus 19 the diameter of which decreases as it moves towards the neck of the interstice 11. As the front meniscus 18 of the droplet reaches the pad 4, liquid begirls to become absorbed by the fibers of the pad as indicated by the arrows 20. As soon as the surface tension of the front meniscus 18, which increases, becomes greater than that of the rear meniscus 19, which decreases, the droplet no longer needs pressure from the infants skin to proceed through the interstice 11 but does so under the effect of the capillary forces. Its rear meniscus 19 then moves away from the skin 16 (FIG. 9) and the whole droplet gradually becomes absorbed by the pad 4 as shown in FIG. 10. As long as the absorption is effective to retain the liquid within the pad 4 and since the skin 16 is spaced from the pad 4 by the fabric 1, the skin lcan no longer come into contact with the liquid thus removed from it.

The polyolens and more particularly polypropylene are not thermoplastic as is polyvinyl chloride but have sharp melting points well above the boiling point of water, so that the polyolen fabric can be laundered by conventional methods without special precautions. However, its extremely repellent properties diminish altogether the need for laundering.

It will be understood that my invention is not limited to the swathing means as shown in FIGS. l to 4 but comprises every arrangement comprising an inner layer of non-absorbent, water-repellent fabric made from polyolefin fibers and having the required properties. In particular, it also comprises diapers consisting solely of.a piece of such fabric and adapted to be lodged between the infants skin and any separate absorbent means such as absorbent sheets, linings, panties, and the like.

What I claim is:

1. Swathing means for infants comprising an inner layer of fabric made from substantially non-absorbent and water-repellent polyolen ber yarn, said fabric forming a plurality of interstices the average cross-sectional arca of each of which is comprised between 750 millionths and 1100 millionths of a square inch.

2. Swathing means for infants comprising an inner layer of looped fabric made from substantially non-absorbent and water-repellent polyolen fiber yarn, said yarn having a count comprised between 285 and 450 deniersl and said looped fabric made therefrom forming a plurality of interstices the average cross-sectional area of each of which is comprised betwen 2.4 millionths and- 2.75 millionths of a square inch per denier of said yarn.

3. Swathing means for infants comprising an inner layer of looped fabric made from substantially non-absorbent and water-repellent polyolen ber yarn, said yarn having a count comprised between 285 and 450 deniers and said looped fabric -rnade therefrom forming a plurality of interstices the average cross-sectional area of each of which is comprised between 750 millionths and 1100 millionths of a square inch.

4. The swathing means for infants as claimed in claim 1 in which said fabric is a looped fabric knitted in 1:1

. ribbed fashion with a number of wales per inch, as measured in the course-wise direction, comprised between 0.5 and 0.7 the number of courses per inch, measuredill the Wale-wise direction,

5. The Swathing means for infants as claimed in claim l in which said looped fabric is made from yarn consisting of polypropylene fibers.

6. A swathing means for infants, comprising an outer water-absorbent layer and an inner non-absorbent and water-repellent layer constituted of a polyoleiin knitted fabric in which the number of wales per inch is from 0.5 to 0.7 the number of courses per inch, said knitted :fabric defining a plurality of interstices the average cross sectional area of each of which is between 750 millionths and 1100 millionths of a square inch and which area is between 2.4 millionths and 2.75 millionths of a square inch per denier of the constituent polyolefin yarn.

7. The swathing means for infants as defined in claim 6, in which said fabric is constituted of a substantially non-absorbent and water-repellent polyolen fiber yarn having a count of between 285 and 450 denier.

8, The swathing means for infants as defined in claim 6, in which said polyolen fabric is knitted in 1:1 ribbed fashion.

9. The swathing means for infants as defined in claim 6, in which said polyoleiin fabric is constituted of a polypropylene fiber yarn.

References Cited by the Examiner UNITED STATES PATENTS 2,695,025 11/54 Andrews 128-287 2,894,511 7/59` Devaud 12S-290 2,905,176 9/59 Davidson 12S-284 2,931,360 4/60 Dexter 12S-284 3,063,452 11/62 Del Guercio 12S-284 3,063,454 11/62 Coates et al. 12S-290 3,089,492 5/63 Owens 128-268 RICHARD A. GAUDET, Primary Examiner. JORDAN FRANKLIN, Examiner. 

1. SWATHING MEANS FOR INFANTS COMPRISING AN INNER LAYER OF FABRIC MADE FROM SUBSTANTIALLY NON-ABSORBENT AND WATER-REPELLENT POLYOLEFIN FIBER YARN, SAID FABRIC FORMING A PLURALITY OF INTERSTICES THE AVERAGE CROSS-SECTIONAL AREA OF EACH OF WHICH IS COMPRISED BETWEEN 750 MILLIONTHS AND 1100MILLIONTHS OF A SQUARE INCH. 